@panos29 It's more about the ADC range, which is about 0.07 - 1.1V for the reading between 0 and 4096. I assume you would always need some kind of pre-amplifier/buffer, at least to protect the esp32 against damage,, and if you do not need to take values at hight speed, you can always use averaging to reduce the noise.
The esp32 chip is told to have a built-in preamplifier, but that is not supported by Micropython, and I do not know whether it works.

Android and WiPy
I' m working with this app from 2016 without problems.
Remarks!! The used Android apps that I am using
from the 2016 are the one that I find when I faced
the same question that you have.
Install(*) from Google Play Store the
Mocha Telnet free application to open a micropython REPL session. To load drivers on WiPy boards, install AndFTP ( in my case) .
Connect to WiFi WiPy network using www.wipy.io as password.
In order to get the Python REPL, open
MochaTelnet and from the menu select
Telnet Settings and enter the IP 192.168.1.1 ( for WiPy 1.0) or IP 192.168.4.1 ( for WiPy 2.0 and LoPy) and the Telnet port number 23.
Now return to main menu of Mocha Telnet
an select Connect and at the login prompt
in telnet terminal enter micro and
at password prompt enter python.
That is all.
Federico Monaldi -July 10 2016